JP5798901B2 - Toner for electrophotography - Google Patents

Description

  The present invention relates to an electrophotographic toner and a method for producing an electrophotographic toner.

In the field of electrophotographic toner, with development of an electrophotographic system, development of a toner corresponding to high image quality and high speed is required.
In order to meet the demands for higher image quality and higher speed, the toner is also required to have various performances, and in order to satisfy the demand, a toner having an intermediate layer in addition to the core-shell structure has been proposed.
For example, in Patent Document 1, the core part has a glass transition point of 20 to 40 ° C. and the shell part has a glass transition point of 50 to 100 ° C. for the purpose of improving low-temperature fixability and offset property. An electrostatic image developing toner having an intermediate layer containing a hydrocarbon compound therebetween is disclosed.
Patent Document 2 discloses, for the purpose of improving peelability and low-temperature fixability, a crystalline resin, a core layer containing at least a colorant, a wax layer containing a release agent that coats the core layer, and the wax layer. And an electrostatic charge image developing toner having a shell layer containing an amorphous resin for coating.
Patent Document 3 discloses an electrostatic charge image developing toner containing toner particles having an intermediate layer and a shell layer on the surface of a core particle for the purpose of improving low-temperature fixability and heat-resistant storage stability. Discloses a toner for developing an electrostatic image, which contains at least a wax and a crystalline polyester resin having a softening point of 60 to 120 ° C. and 70 to 100% by weight of the whole shell layer constituting resin.

JP 2007-212871 A JP 2005-227671 A JP 2005-99081 A

  An object of the present invention is to provide an electrophotographic toner having a small amount of fine powder and excellent in low-temperature fixability, and a method for producing the same.

Although Patent Documents 1 to 3 disclose the final physical properties of the toner, they do not disclose any physical properties at the time of preparing the core and the intermediate layer and the influence of the physical properties on the toner evaluation.
The present inventors paid attention to the fact that fine powder may be generated when an intermediate part is formed between the core part and the shell part, and that the chargeability is reduced when the fine powder is generated.
As a result, it has been found that, in a toner having a core part, an intermediate part and a shell part, a toner having a small amount of fine powder and excellent in low-temperature fixability can be produced by containing a specific amount of a release agent in the core part.
This is because the resin particles (A) containing the polyester resin (a) and the release agent particles are aggregated by the flocculant when the core portion is formed, and the release agent particles are taken into the core portion. When the resin particles (B) containing the polyester resin (b) and the release agent particles are attached, it is considered that the release agent particles are not easily attached to the core particles, and are thus easily detached from the intermediate portion.

That is, the present invention provides the following [1] and [2].
[1] A core portion containing a polyester resin (a) and a release agent , a polyester resin (b) which is the same or different from the polyester resin (a) and an intermediate portion containing a release agent, and a polyester resin (a ) And a toner for electrophotography comprising a polyester resin (c) which is the same or different resin, and the contents of the release agent contained in the core part, the intermediate part and the shell part are respectively In order, 3 to 15% by weight with respect to the weight of the core part, 1 to 10% by weight with respect to the weight of the intermediate part, and 0.5% by weight or less with respect to the weight of the shell part . An electrophotographic toner comprising 65% by weight or more and less than 90% by weight in the core part based on the total amount.
[2] The method for producing an electrophotographic toner according to [1], including the following steps (1) to (3).
Step (1): Step of aggregating resin particles (A) containing polyester resin (a) and release agent particles in an aqueous medium to obtain core particles Step (2): Polyester resin (b Step of obtaining the core-shell particles (1) by adhering the resin particles (B) containing the resin particles (B) and the release agent particles Step (3): Resin particles (C) containing the polyester resin (c) in the core-shell particles (1) Core-shell particles comprising a core part containing a polyester resin (a) and a release agent, an intermediate part containing a polyester resin (b) and a release agent, and a shell part containing a polyester resin (c) Step of obtaining (2)

  According to the present invention, it is possible to provide an electrophotographic toner having a small amount of fine powder and excellent in low-temperature fixability and a method for producing the same.

The electrophotographic toner of the present invention comprises a core portion containing a polyester resin (a) and a release agent, an intermediate portion containing a polyester resin (b) and a release agent, and a shell portion containing a polyester resin (c). Consists of.
In the present invention, the toner core portion is the innermost layer portion constituting the toner, and the shell portion is the outermost layer portion constituting the toner. The middle layer is called the middle part.
The intermediate portion may be a multilayer, and preferably 1 to 5 layers. Even if the layer of the intermediate part has the same composition, it can be made into a multilayer by repeating the step (2) described later.

In the toner for electrophotography of the present invention, the core portion contains 65 wt% or more and less than 90 wt% with respect to the total amount of the release agent in the toner. As a result, it is possible to obtain a toner excellent in low-temperature fixability while suppressing the generation of fine powder during toner preparation. The content of the release agent in the core is preferably 70% by weight or more, more preferably 75% by weight or more based on the total amount in the toner from the viewpoint of the amount of fine powder, and from the viewpoint of fixability. , Preferably 88 wt% or less, more preferably 85 wt% or less, preferably 70 to 88 wt%, more preferably 75 to 85 wt%.
In the electrophotographic toner of the present invention, the content of the release agent in the intermediate part is preferably more than 10% by weight and not more than 35% by weight, more preferably 12-30, relative to the total amount of the release agent in the toner. % By weight, more preferably 15 to 25% by weight. As a result, it is possible to obtain a toner excellent in low-temperature fixability while suppressing the generation of fine powder during toner preparation.
In the electrophotographic toner of the present invention, the content of the release agent contained in the shell portion is preferably 5% by weight or less based on the total amount of the release agent in the toner, from the viewpoint of suppressing the generation of fine powder. % By weight or less is more preferred, 1% by weight or less is more preferred, and it is even more preferred that no substantial content is contained.
The total content of the release agent in the electrophotographic toner of the present invention is preferably 1 to 10% by weight, more preferably 2 to 8% by weight, and even more preferably 2 to 6% by weight based on the toner weight.
The weight ratio ((a) / (b)) between the polyester resin (a) contained in the core part and the polyester resin (b) contained in the intermediate part is the viewpoint of the minimum fixing temperature of the toner and the circularity of the particles. Therefore, it is preferably 90/10 to 35/65, more preferably 75/25 to 35/65, still more preferably 75/25 to 45/55, and still more preferably 70/30 to 50/50.
Weight ratio of the polyester resin (a) contained in the core part and the polyester resin (b) contained in the intermediate part to the polyester resin (c) contained in the shell part [(core part + intermediate part) / shell part] Is preferably 85/15 to 55/45, more preferably 80/20 to 60/40, and even more preferably 75/25 to 60/40, from the viewpoint of the minimum fixing temperature and storage durability of the toner.
For the total content of the polyester resin in the toner (the total amount of the polyester resin (a) contained in the core part, the polyester resin (b) contained in the intermediate part and the polyester resin (c) contained in the shell part)) The content of the polyester resin (a) in the core is preferably 10 to 70% by weight, more preferably 15 to 60% by weight, and still more preferably 20 to 20% from the viewpoint of the minimum fixing temperature of the toner and the circularity of the particles. The content of the polyester resin (b) in the middle part is preferably 5 to 60% by weight, more preferably 10 to 55% by weight, and still more preferably 15 to 50% by weight. The content of the polyester resin (c) is preferably 5 to 50% by weight, more preferably 10 to 45% by weight, and still more preferably 20 to 40% by weight.

[Core]
The core part contains a polyester resin (a) and a release agent. The polyester resin (a) in the core part is a resin constituting the core particles obtained in the step (1) of the method for producing an electrophotographic toner described later.

(Polyester resin (a))
Hereinafter, although the polyester resin (a) contained in a core part is demonstrated, the suitable range is the same also about the polyester resins (b) and (c) mentioned later.
In the present invention, the polyester resin (a) is preferably a cross-linked polyester resin from the viewpoint of improving toner fixability. The crosslinked polyester resin can be obtained using a trivalent or higher polyvalent carboxylic acid and / or a trivalent or higher polyhydric alcohol described later.
The polyester resin (a) preferably contains an amorphous polyester from the viewpoint of improving the chargeability of the toner. Amorphous polyester is a crystal defined by the ratio between the softening point and the maximum endothermic peak temperature measured by a differential scanning calorimeter (DSC), (softening point (° C)) / (maximum endothermic peak temperature (° C)). A polyester having a sex index greater than 1.4 or less than 0.6. On the other hand, the crystalline polyester is a polyester having a crystallinity index of 0.6 to 1.4, preferably 0.8 to 1.1.
The crystallinity index of the polyester resin (a) is preferably less than 0.6 or more than 1.4 and 4 or less, more preferably less than 0.6 or 1.5 or more and 4 or less, from the viewpoint of low-temperature fixability of the toner. More preferably, it is less than 0.6 or 1.5 or more and 3 or less, More preferably, it is less than 0.6 or 1.5 or more and 2 or less. The crystallinity index can be appropriately determined depending on the type and ratio of raw material monomers, production conditions (for example, reaction temperature, reaction time, cooling rate), and the like.

The polyester resin (a) preferably has an acid group at the molecular end from the viewpoint of emulsifiability. Examples of the acid group include a carboxyl group, a sulfonic acid group, a phosphonic acid group, and a sulfinic acid. Among these, a carboxyl group is preferable from the viewpoint of achieving both the dispersibility of the resin and the storage stability of the toner.
The acid value of the polyester resin (a) is preferably 6 to 35 mgKOH / g, more preferably 10 to 35 mgKOH / g, still more preferably 15 to 35 mgKOH / g, from the viewpoint of emulsification in the aqueous medium of the resin.

The glass transition point of the polyester resin (a) is preferably 55 to 75 ° C., more preferably 55 to 70 ° C., and still more preferably 58 to 68 ° C., from the viewpoint of toner durability, low-temperature fixability and storage stability. is there.
The softening point of the polyester resin (a) is preferably 70 to 165 ° C, more preferably 70 to 140 ° C, still more preferably 90 to 140 ° C, from the viewpoint of toner durability, low-temperature fixability and storage stability. Preferably it is 100-130 degreeC.
In addition, when using 2 or more types of polyester resin (a) in mixture, the glass transition point and softening point are obtained by the method of an Example as a mixture of 2 or more types of polyester resins (a), respectively. The glass transition point and softening point.

The polyester resin (a) preferably contains two kinds of polyesters having different softening points from the viewpoints of low-temperature fixability, offset resistance and durability of the toner. When two types of polyesters having different softening points are polyesters (a-1) and (a-2), respectively, the softening point of one polyester (a-1) is preferably 70 ° C. or higher and lower than 115 ° C., and the other polyester The softening point of (a-2) is preferably 115 ° C. or higher and 165 ° C. or lower. The weight ratio of polyester (a-1) to polyester (a-2) ((a-1) / (a-2)) is preferably 10/90 to 90/10, more preferably 50/50 to 90. / 10.
The polyester resin (a) preferably contains a crystalline polyester and an amorphous polyester from the viewpoint of low-temperature fixability and storage stability of the toner. The weight ratio of crystalline polyester / amorphous polyester (crystalline polyester / amorphous polyester) is preferably 50/50 to 5/95, more preferably 70/30 to 10/90.

The polyester resin (a) is obtained by polycondensation reaction between an acid component and an alcohol component. The polycondensation reaction is preferably performed at 180 to 250 ° C. in the presence of a catalyst.
Examples of the acid component include a dicarboxylic acid, a succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, and a polyvalent carboxylic acid having 3 or more valences. Anhydrides and alkyl (C1-C3) esters are also included. Among these, dicarboxylic acid is preferable from the viewpoint of storage stability and chargeability of the toner.
Examples of the dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, fumaric acid, maleic acid, adipic acid, azelaic acid, succinic acid, and cyclohexanedicarboxylic acid. Among these, terephthalic acid is preferable.
Examples of the succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms include dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid.
Examples of the trivalent or higher polyvalent carboxylic acid include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid and the like. Among these, trimellitic acid is preferable from the viewpoint of offset resistance.
These acid components can be used alone or in combination of two or more.
The polyester resin (a) contains an acid component containing a trivalent or higher polyvalent carboxylic acid and its acid anhydride or its alkyl ester, preferably trimellitic acid or its anhydride, from the viewpoint of high temperature offset resistance of the toner. It is preferable to use at least one polyester resin (a) obtained by using the polyester resin.

Examples of the alcohol component include aliphatic diols having 2 to 12 carbon atoms in the main chain, aromatic diols, hydrogenated products of bisphenol A, and trihydric or higher polyhydric alcohols. Among these, amorphous polyesters are used. From the viewpoint of obtaining aromatic diols, aromatic diols are preferred, and alkylenes of bisphenol A such as polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane ( C2-C3) oxide adduct (average addition mole number 1-16) is more preferable.
From the viewpoint of obtaining a crystalline polyester, α, ω-aliphatic diols having 2 to 12 carbon atoms are preferable, and ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1 , 5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol and the like. It is done.
Examples of the trihydric or higher polyhydric alcohol include glycerin and pentaerythritol.
These alcohol components can be used alone or in combination of two or more.

As a catalyst, a tin compound, a titanium compound, etc. are preferable from a viewpoint of the efficiency of a condensation polymerization reaction, and a tin compound is more preferable. Examples of the tin compound include di (2-ethylhexanoic acid) tin and dibutyl tin oxide. Examples of the titanium compound include titanium diisopropylate bistriethanolamate.
Although there is no restriction | limiting in the usage-amount of a catalyst, Preferably it is 0.01-1 weight part with respect to 100 weight part of total amounts of an acid component and an alcohol component, More preferably, it is 0.1-0.6 weight part.

  The polycondensation reaction is preferably carried out by adding an acid component and an alcohol component to a reaction vessel and maintaining at 180 to 250 ° C. for 5 to 15 hours, and then adding a catalyst and maintaining at 180 to 250 ° C. for 1 to 5 hours. More preferably, the reaction is allowed to proceed, and the pressure is reduced to 5.0 to 20 kPa and maintained for 1 to 10 hours.

  In addition, in this invention, what modified | denatured the polyester resin (a) can be used in the range which does not impair the effect. As a method for modifying the polyester resin, for example, grafting with phenol, urethane, epoxy or the like by the method described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc. And a method of forming a block, a method of forming a composite resin having two or more resin units including a polyester unit, and the like. The same applies to the polyester resins (b) and (c) described later.

(Release agent)
As release agents, low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; fatty acid amides such as oleic acid amide and stearic acid amide; plant waxes such as carnauba wax, rice wax and candelilla wax; beeswax and the like Animal waxes: minerals such as montan wax, paraffin wax, Fischer-Tropsch wax, petroleum waxes and the like. These release agents can be used alone or in combination of two or more.
The content of the release agent in the core part is preferably 3 to 15% by weight, more preferably 4 to 15% by weight, and still more preferably 5%, based on the weight of the core part, from the viewpoints of toner fixability and fine powder amount. ~ 13 wt%. In addition, a core part here contains a polyester resin (a), a mold release agent, and a coloring agent.

(Coloring agent)
The core part may contain a colorant.
As the colorant, pigments and dyes are used, and pigments are preferable from the viewpoint of image density of the toner.
Examples of the pigment include carbon black, inorganic composite oxide, chrome yellow, benzidine yellow, brilliantamine 3B, brilliantamine 6B, Bengal, aniline blue, ultramarine blue, copper phthalocyanine, phthalocyanine green, and the like. Copper phthalocyanine is preferred.
Examples of the dye include acridine series, azo series, benzoquinone series, azine series, anthraquinone series, indico series, phthalocyanine series, and aniline black series.
These colorants can be used alone or in combination of two or more.

[Middle part]
The intermediate part contains a polyester resin (b) and a release agent. The polyester resin (b) in the intermediate part is a polyester resin (b) used to form the intermediate part in the step (2) of the electrophotographic toner manufacturing method described later. The intermediate portion may be a single layer or a multilayer.
The physical properties and production method of the polyester resin (b) contained in the intermediate part are the same as those of the polyester resin (a) in the core part. The polyester resin (b) preferably contains an amorphous polyester from the viewpoint of improving the chargeability of the toner.
As the acid component of the polyester resin (b), dicarboxylic acids and trivalent or higher polyvalent carboxylic acids are preferable, and among these, terephthalic acid and trimellitic acid are preferable.
As the alcohol component, aromatic diols are preferable, and alkylenes of bisphenol A such as polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane. (C2-C3) oxide adduct (average added mole number 1-16) is more preferable.
The polyester resin (b) may be the same as or different from the polyester resin (a). However, it is preferable that the polyester resin (b) contains the same alcohol component or acid component as the polyester resin (a) from the viewpoint of improving the fixing property of the toner. It is more preferable to contain both of the acid components, and it is even more preferable to include the same alcohol component and acid component as the polyester resin (a). In particular, the polyester resin (a) and the polyester resin (b) are more preferably the same resin.
The polyester resin (b) is preferably a cross-linked polyester resin from the viewpoint of improving toner fixability.

The release agent contained in the intermediate portion may be the same as or different from the release agent contained in the core portion, but is preferably the same from the viewpoint of toner fixing properties and fine powder amount.
The content of the release agent in the intermediate part is preferably 1 to 10% by weight, more preferably 1 to 8% by weight, and still more preferably 2%, based on the weight of the intermediate part, from the viewpoint of toner fixability and the amount of fine powder. -7% by weight. The intermediate part may contain a colorant. In addition, an intermediate part here contains a polyester resin (b), a mold release agent, and a coloring agent.
The polyester resin (b) preferably contains two kinds of polyesters having different softening points from the viewpoints of low-temperature fixability, offset resistance and durability of the toner. When two types of polyesters having different softening points are polyesters (b-1) and (b-2), respectively, the softening point of one polyester (b-1) is preferably 70 ° C. or higher and lower than 115 ° C., and the other polyester The softening point of (b-2) is preferably 115 ° C. or higher and 165 ° C. or lower. The weight ratio of polyester (b-1) to polyester (b-2) ((b-1) / (b-2)) is preferably 10/90 to 90/10, more preferably 50/50 to 90. / 10.
The polyester resin (b) preferably contains a crystalline polyester and an amorphous polyester from the viewpoint of low-temperature fixability and storage stability of the toner. The weight ratio of crystalline polyester / amorphous polyester (crystalline polyester / amorphous polyester) is preferably 50/50 to 5/95, more preferably 70/30 to 10/90.

[Shell part]
The shell portion contains a polyester resin (c). The polyester resin (c) of the shell part is a polyester resin (c) used for forming the shell part in step (3) of the electrophotographic toner manufacturing method described later.
The physical properties and production method of the polyester resin (c) contained in the shell part are basically the same as those of the polyester resins (a) and (b) described above.
As the acid component of the polyester resin (c), dicarboxylic acids and trivalent or higher polyvalent carboxylic acids are preferable, and among these, terephthalic acid and trimellitic acid are preferable.
As the alcohol component, aromatic diols are preferable, and alkylenes of bisphenol A such as polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane. (C2-C3) oxide adduct (average added mole number 1-16) is more preferable.
The polyester resin (c) may be the same as or different from the polyester resin (a). However, it is preferable that the polyester resin (c) contains the same alcohol component or acid component as the polyester resin (a) from the viewpoint of improving the fixing property of the toner. More preferably, both of the same acid components are contained.
From the viewpoint of improving the durability and chargeability of the toner, the polyester resin (c) is preferably 70 to 100% by weight of amorphous polyester, more preferably 80 to 100%, based on the total amount of the polyester resin (c). It is preferable to contain 100% by weight, more preferably substantially 100% by weight. As described above, the amorphous polyester is a polyester having a crystallinity index of more than 1.4 or less than 0.6.
The polyester resin (c) preferably contains two kinds of polyesters having different softening points from the viewpoint of low-temperature fixability, offset resistance and durability of the toner. When two types of polyesters having different softening points are polyesters (c-1) and (c-2), respectively, the softening point of one polyester (c-1) is preferably 70 ° C. or higher and lower than 115 ° C., and the other polyester The softening point of (c-2) is preferably 115 ° C. or higher and 165 ° C. or lower. The weight ratio of polyester (c-1) to polyester (c-2) ((c-1) / (c-2)) is preferably 10/90 to 90/10, more preferably 50/50 to 90. / 10.
Further, in the shell part, from the viewpoint of improving the charging property, durability and heat-resistant storage stability of the toner, the content of the release agent in the shell part is preferably 0.5% by weight or less with respect to the shell part weight, It is preferable that substantially no release agent is contained.
Furthermore, the shell part may contain a colorant, but the content of the colorant in the shell part is preferably 0.5% by weight or less with respect to the weight of the shell part, and substantially does not contain the colorant. Is preferred. Also when it contains a coloring agent, it is preferable that it is a quantity smaller than an intermediate part. Here, the shell portion includes a polyester resin (c), a release agent, and a colorant.
More preferably, the shell part does not substantially contain any of a release agent and a colorant.

[Method for producing toner for electrophotography]
The method for producing an electrophotographic toner of the present invention preferably includes the following steps (1) to (3).
Step (1): Resin particles (A1) containing polyester resin (a) and release agent particles, or resin particles (A2) containing polyester resin (a) and colorant and release agent particles are used in an aqueous medium. Step of agglomerating to obtain core particles Step (2): Resin particles (B1) containing polyester resin (b) and release agent particles, or polyester resin (b) and colorant are added to the core particles. The step of obtaining the core-shell particles (1) by adhering the resin particles (B2) containing and the release agent particles Step (3): The resin particles (C) containing the polyester resin (c) in the core-shell particles (1). Core shell particles comprising a core part containing a polyester resin (a) and a release agent, an intermediate part containing a polyester resin (b) and a release agent, and a shell part containing a polyester resin (c) 2) get Degree

[Step (1)]
In the step (1), the resin particles (A1) containing the polyester resin (a) and the release agent particles, or the resin particles (A2) containing the polyester resin (a) and the colorant and the release agent particles are aqueous. It is a step of agglomerating in a medium to obtain core particles.

In this step, first, resin particles (A1) containing a polyester resin (a) and release agent particles, or resin particles (A2) containing a polyester resin (a) and a colorant and release agent particles are used. Mix in an aqueous medium to obtain a mixed dispersion. Hereinafter, the resin particles (A1) and the resin particles (A2) are collectively referred to as resin particles (A).
The colorant may be mixed as particles independent of the resin particles or may be included in the resin particles, but is included in the resin particles from the viewpoint of suppressing the generation of coarse particles during aggregation. It is preferable. That is, it is preferable that the resin particles (A2) containing the polyester resin (a) and the colorant and the release agent particles are mixed in an aqueous medium to obtain a mixed dispersion.
In this step, resin particles other than the resin particles (A) may be mixed. As resin particles other than the resin particles (A), resin particles containing amorphous polyester are preferable, and resin particles similar to the resin particles (B) described later are more preferable.
There is no restriction | limiting in order of mixing, You may add any in order and may add simultaneously.

The content of the resin particles (A) is preferably 10 to 40 parts by weight, more preferably 20 to 30 parts by weight in the mixed dispersion. The content of the aqueous medium is preferably 60 to 90 parts by weight, more preferably 70 to 80 parts by weight in the mixed dispersion. The content of the release agent particles is preferably 1 to 20 parts by weight, more preferably 5 to 15 parts by weight with respect to 100 parts by weight of the resin of the core part from the viewpoint of toner releasability and chargeability. .
In step (1), a colorant may be mixed. When the colorant is mixed, the content is preferably 1 to 20 parts by weight, more preferably 3 to 15 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles (A) from the viewpoint of image density. It is.
The mixing temperature is preferably 0 to 40 ° C. from the viewpoint of aggregation control.

[Resin Particles Containing Polyester Resin (a) (A)]
The resin particles (A) contain a polyester resin (a). The content of the polyester resin (a) in the resin particles (A) is preferably from 50 to the resin constituting the resin particles (A) from the viewpoint of improving the low-temperature fixability of the toner and preventing hot offset. It is 100% by weight, more preferably 70 to 100% by weight, still more preferably 80 to 100% by weight.

The resin particles (A) may contain a resin other than the polyester resin (a), for example, a resin such as a styrene acrylic copolymer, an epoxy resin, a polycarbonate, and a polyurethane, as long as the effects of the present invention are not impaired.
Moreover, it is preferable that a resin particle (A) is a resin particle (A2) containing the coloring agent containing a coloring agent from a viewpoint of suppressing generation | occurrence | production of a coarse particle at the time of aggregation.
When the resin particles (A) are resin particles (A2) containing a colorant, the content of the colorant is based on 100 parts by weight of the resin constituting the resin particles (A2) from the viewpoint of toner image density. Preferably it is 1-20 weight part, More preferably, it is 5-10 weight part.
The resin particles (A) may contain a release agent and a charge control agent. Moreover, you may contain additives, such as reinforcement fillers, such as a fibrous material, antioxidant, and anti-aging agent, as needed.

(Production of resin particles (A))
The resin particles (A) are preferably produced by a method in which a resin containing the polyester resin (a) and the above-mentioned optional components are dispersed in an aqueous medium to obtain a dispersion containing the resin particles (A).
Examples of the method for obtaining a dispersion include a method in which a resin or the like is added to an aqueous medium and a dispersion treatment or the like is performed, a method in which an aqueous medium is gradually added to the resin or the like and phase inversion emulsification is performed, and the like. From the viewpoint of obtaining resin particles having a diameter and improving the aggregation control during toner production, a method using phase inversion emulsification is preferred. Hereinafter, a method by phase inversion emulsification will be described.

First, the resin containing the polyester resin (a), the alkaline aqueous solution, and the above-mentioned optional components are melted and mixed to obtain a resin mixture.
When the resin containing the polyester resin (a) is composed of a plurality of resins, a mixture of the polyester resin (a) and other resins may be used in advance, but the alkaline aqueous solution and optional components are added. It may be obtained by adding at the same time, melting and mixing. For example, from the viewpoint of obtaining resin particles having a small particle diameter, a method of obtaining a resin mixture by melting and mixing the polyester resin (a), the alkaline aqueous solution, and the above-mentioned optional components is preferable.
In mixing, it is preferable to add a surfactant from the viewpoint of the emulsion stability of the resin.

  Examples of the alkali in the alkaline aqueous solution include hydroxides of alkali metals such as potassium hydroxide and sodium hydroxide, and ammonia. From the viewpoint of improving the dispersibility of the resin, potassium hydroxide and sodium hydroxide may be used. preferable. The concentration of alkali in the aqueous alkali solution is preferably 1 to 30% by weight, more preferably 1 to 25% by weight, and still more preferably 1.5 to 20% by weight. Since alkali is used to neutralize the acid group at the molecular chain end of the polyester resin (a), it is considered that the dispersibility of the resin is improved by the alkali.

Examples of the surfactant include nonionic surfactants, anionic surfactants, and cationic surfactants. Among them, nonionic surfactants are preferable, and nonionic surfactants and anionic surfactants are preferred. It is more preferable to use an active agent or a cationic surfactant in combination, and it is more preferable to use a nonionic surfactant and an anionic surfactant in combination from the viewpoint of sufficiently emulsifying the resin.
When a nonionic surfactant and an anionic surfactant are used in combination, the weight ratio of the nonionic surfactant to the anionic surfactant (nonionic surfactant / anionic surfactant) is: From the viewpoint of sufficiently emulsifying the resin, it is preferably 0.3 to 10, more preferably 0.5 to 5.

Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl aryl ethers such as polyoxyethylene lauryl ether, polyoxyethylene alkyl ethers, polyethylene glycol monolaurate , Polyoxyethylene fatty acid esters such as polyethylene glycol monostearate and polyethylene glycol monooleate, and oxyethylene / oxypropylene block copolymers. Among these, from the viewpoint of emulsion stability of the resin, polyoxyethylene fatty acid esters Ethylene alkyl ethers are preferred.
Examples of anionic surfactants include dodecyl benzene sulfonic acid, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium alkyl ether sulfate, etc. Among these, from the viewpoint of emulsion stability of the resin, sodium dodecyl benzene sulfonate Sodium alkyl ether sulfate is preferred.
Examples of the cationic surfactant include alkylbenzene dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, distearyl ammonium chloride and the like.

  The content of the surfactant is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, still more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles (A). More preferably, it is 0.5 to 10 parts by weight.

As a method for obtaining a resin mixture, a resin containing a polyester resin (a), an alkaline aqueous solution, and the above optional components, preferably a surfactant, are placed in a container, and the resin is melted uniformly while stirring with a stirrer. A method of mixing is preferred.
The temperature at which the resin is melted and mixed is preferably equal to or higher than the glass transition point of the polyester resin (a).

Next, an aqueous medium is added to the resin mixture and phase inversion is performed to obtain a dispersion containing resin particles (A).
As the aqueous medium, those containing water as a main component are preferable. From the viewpoint of environmental properties, the content of water in the aqueous medium is preferably 80% by weight or more, more preferably 90% by weight or more, and still more preferably 95% by weight. % Or more, more preferably substantially 100% by weight. The water used is preferably deionized water or distilled water.
The temperature at which the aqueous medium is added is preferably equal to or higher than the glass transition point of the polyester resin (a) from the viewpoint of obtaining homogeneous resin particles having a small particle diameter.

  The addition rate of the aqueous medium is preferably 0.1 to 50 weights with respect to 100 parts by weight of the resin constituting the resin particles (A) until the phase inversion is completed from the viewpoint of making the resin particles have a small particle size. Part / minute, more preferably 0.1 to 30 parts by weight / minute, still more preferably 0.5 to 10 parts by weight / minute, still more preferably 0.5 to 5 parts by weight / minute. In addition, there is no restriction | limiting in the addition rate of the aqueous medium after completion | finish of phase inversion.

  The amount of the aqueous medium used is preferably 100 to 2000 parts by weight, more preferably 150 to 100 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles (A) from the viewpoint of obtaining uniform aggregated particles in the subsequent aggregation step. 1500 parts by weight, more preferably 150 to 500 parts by weight. The solid content concentration is preferably 7 to 50% by weight, more preferably 10 to 40% by weight, still more preferably 20 to 40% by weight, from the viewpoint of the stability and ease of handling of the obtained resin particle dispersion. More preferably, it is 25 to 35% by weight. In addition, solid content is the total amount of non-volatile components, such as resin and surfactant.

  From the viewpoint of improving the heat resistant storage stability and fixability of the toner, the polyester resin (a) contained in the resin particles (A) is preferably crosslinked, and more preferably crosslinked with a compound having an oxazoline group.

As the compound having an oxazoline group, a compound containing a plurality of oxazoline groups in the molecule can be used, but a polymer containing an oxazoline group is preferred. The weight average molecular weight is preferably 500 to 2,000,000, more preferably 1,000 to 1,000,000 from the viewpoint of reactivity with the polyester resin.
Examples of commercially available polymers containing oxazoline groups include EPOCROSS WS series (water-soluble type, main chain acrylic), K series (emulsion type, main chain styrene / acrylic) manufactured by Nippon Shokubai Co., Ltd. Also product name).
The content or addition amount of the compound having an oxazoline group is preferably 0.1 to 30 as a solid content with respect to 100 parts by weight of the resin in the resin dispersion, from the viewpoint of crosslinking reactivity with the resin and productivity. Part by weight, more preferably 1 to 20 parts by weight.

  When a compound having an oxazoline group is added and mixed at a predetermined temperature, a part of the resin particles dispersed in the resin dispersion is cross-linked. The temperature at this time is preferably 60 to 100 ° C, more preferably 70 to 98 ° C. The presence of crosslinking of the resin by the compound having an oxazoline group can be confirmed by an amide group generated by crosslinking.

Thus, the volume median particle size of the resin particles (A) in the dispersion containing the obtained resin particles (A) is preferably 0.02 to 2 μm from the viewpoint of obtaining a high-image toner. More preferably, it is 0.02-1.5 micrometers, More preferably, it is 0.05-1 micrometer, More preferably, it is 0.05-0.5 micrometer. Here, the volume-median particle size is a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size.
The coefficient of variation (CV value) (%) of the particle size distribution of the resin particles is preferably 40% or less, more preferably 35% or less, still more preferably 30% or less, and still more preferably, from the viewpoint of obtaining a high-image toner. Is 28% or less. The CV value is a value represented by the following formula, and is specifically obtained by the method described in the examples.
CV value (%) = [standard deviation of particle size distribution (μm) / volume median particle size (μm)] × 100

The release agent particles preferably contain the above-mentioned surfactant from the viewpoint of cohesiveness. In the case of using the surfactant, the content is preferably 0.01 to 10 parts by weight, more preferably 0.1 parts by weight with respect to 100 parts by weight of the release agent, from the viewpoints of aggregability and chargeability of the obtained toner. 1 to 5 parts by weight.
The volume median particle size of the release agent particles is preferably from 0.1 to 1 μm, more preferably from 0.1 to 0.7 μm, still more preferably from the viewpoint of preventing chargeability and hot offset of the obtained toner. 1 to 0.5 μm.
The CV value of the release agent particles is preferably 15 to 50%, more preferably 15 to 40%, and still more preferably 15 to 35%, from the viewpoint of the chargeability of the obtained toner.

(Manufacture of core particles)
Next, the particles in the mixed dispersion, that is, the resin particles (A1) containing the polyester resin (a) and the release agent particles, or the resin particles (A2) containing the polyester resin (a) and the colorant are released. The agent particles are aggregated in an aqueous medium to obtain a dispersion of core particles (hereinafter also referred to as “core particle dispersion”).
Here, it is preferable to aggregate the resin particles (A2) containing the polyester resin (a) and the colorant and the release agent particles in an aqueous medium from the viewpoint of suppressing the generation of coarse particles during aggregation.
In this step, it is preferable to add a flocculant for efficient aggregation.
Examples of the aggregating agent include a quaternary salt cationic surfactant, an organic aggregating agent such as polyethyleneimine; an inorganic aggregating agent such as an inorganic metal salt, an inorganic ammonium salt, and a bivalent or higher metal complex.
Examples of the inorganic metal salt include metal salts such as sodium sulfate, sodium chloride, calcium chloride and calcium nitrate, and inorganic metal salt polymers such as polyaluminum chloride and polyaluminum hydroxide. Examples of the inorganic ammonium salt include ammonium sulfate, ammonium chloride, ammonium nitrate and the like, and ammonium sulfate is more preferable.
The use amount of the flocculant is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and further preferably 30 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles (A), from the viewpoint of chargeability of the toner. Less than parts by weight. From the viewpoint of the cohesiveness of the resin particles, the amount is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and still more preferably 5 parts by weight or more with respect to 100 parts by weight of the resin constituting the resin particles (A). is there. In consideration of the above points, the amount of the monovalent salt used is preferably 1 to 50 parts by weight, more preferably 3 to 40 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles (A). More preferably, it is 5-30 weight part.

  As an aggregating method, an aggregating agent is preferably added dropwise as an aqueous solution to a container containing a mixed dispersion. The flocculant may be added at one time, or may be added intermittently or continuously. However, it is preferable to perform sufficient stirring at the time of addition and after completion of the addition. From the viewpoint of aggregation control and shortening of toner production time, the dropping time of the aggregating agent is preferably 1 to 120 minutes. The dropping temperature is preferably 0 to 40 ° C. from the viewpoint of controlling aggregation.

  The volume median particle size of the obtained core particles is preferably 1 to 10 μm, more preferably 2 to 9 μm, and further preferably 3 to 6 μm, from the viewpoint of improving the image quality of an image obtained using the toner. The CV value is preferably 30% or less, more preferably 28% or less, and still more preferably 25% or less.

[Step (2)]
In the step (2), the resin particles (B1) containing the polyester resin (b) and the release agent particles are used as the core particles, or the resin particles (B2) containing the polyester resin (b) and the colorant and the release agent. In this step, the core-shell particles (1) are obtained by attaching the particles. The core-shell particles (1) constitute a core part and an intermediate part in the obtained toner. Hereinafter, the resin particles (B1) and the resin particles (B2) are collectively referred to as resin particles (B).
The colorant may be attached to the core particles as particles independent of the resin particles or may be contained in the resin particles, but it improves the toner image density and suppresses the generation of coarse particles during aggregation. Therefore, it is preferable that it is contained in the resin particles. That is, it is preferable to obtain the core-shell particles (1) having a two-layer structure by attaching the resin particles (B2) containing the polyester resin (b) and the colorant.
In this step, first, a dispersion of resin particles (B) containing a polyester resin (b) (hereinafter also referred to as “resin particle (B) dispersion”) was prepared, and then obtained in step (1). It is preferable to add the resin particle (B) dispersion liquid to the core particle dispersion liquid to adhere the resin particles (B) to the core particles to obtain the core shell particles (1).
The resin particles (B) are preferably resin particles (B2) containing a colorant from the viewpoint of improving the toner image density and suppressing the generation of coarse particles during aggregation.
The resin particles (B) can be obtained by the same method as the resin particles (A).
When the resin particles (B) are resin particles (B2) containing a colorant, the content of the colorant is based on 100 parts by weight of the resin constituting the resin particles (B) from the viewpoint of the image density of the toner. Preferably it is 1-20 weight part, More preferably, it is 5-10 weight part.

When adding the resin particle (B) dispersion, it is preferable to use the aggregating agent in order to efficiently attach the resin particles (B) to the core particles.
As an addition method when adding the resin particle (B) dispersion, the coagulant and the resin particle (B) dispersion are added simultaneously, and the coagulant and the resin particle (B) dispersion are added alternately. The method is preferably a method of adding the resin particle (B) dispersion while gradually raising the temperature of the core particle dispersion. According to such a method, it is possible to prevent a decrease in cohesiveness of the core particles and the resin particles (B) due to a decrease in the coagulant concentration.

  The temperature in the system in this step is more preferably 5 ° C. or more lower than the glass transition point of the polyester resin (b) from the viewpoint of improving the image quality of the image obtained using the toner. By producing the core-shell particles (1) in the temperature range, the generation of coarse particles can be suppressed and a toner with a sharp particle size distribution can be obtained.

  The amount of the resin particles (B) added to the core particle dispersion is determined by the weight ratio of the resin particles (B) to the resin particles (A) (resin particles (B ) / Resin particles (A)) is preferably 0.3 to 1.5, more preferably 0.3 to 1.0, and still more preferably 0.35 to 0.75.

  The resin particle (B) dispersion may be added continuously over a certain period of time, may be added at once, or may be added in multiple portions, but the resin particles (B) From the viewpoint of facilitating selective aggregation to the core particles, it is preferable to add continuously over a certain period of time, or to add divided into multiple times, among them, the viewpoint of promoting selective aggregation and It is more preferable to add continuously over a certain time from the viewpoint of production efficiency. The addition time in the case of continuous addition is preferably 1 to 10 hours, more preferably 3 to 8 hours from the viewpoint of obtaining uniform core-shell particles (1) and shortening of the production time.

The volume median particle size of the core-shell particles (1) obtained in the step (2) is preferably 1 to 10 μm, more preferably 2 to 10 μm, still more preferably 3 to 9 μm, from the viewpoint of improving the image quality of the toner. Preferably it is 4-6 micrometers.
The circularity of the core-shell particles (1) is preferably 0.930 to 0.980, more preferably 0.935 to 0.980, and still more preferably 0.940, from the viewpoint of chargeability and cleaning properties of the toner obtained. ~ 0.975. When the circularity of the core-shell particles (1) is high, the circularity of the obtained toner is also high.
The amount of fine powder at the time of preparing the core-shell particles (1) is preferably 0 to 10% or less, more preferably 0 to 7%, and still more preferably 0 to 5% from the viewpoint of chargeability. When the amount of fine powder of the core-shell particles (1) is small, the amount of fine powder of the toner obtained is also small.

[Step (3)]
In step (3), resin particles (C) containing a polyester resin (c) are attached to the core-shell particles (1), and the core portion containing the polyester resin (a) and the release agent, the polyester resin (b) And a core-shell particle (2) comprising an intermediate part containing a release agent and a shell part containing a polyester resin (c).
The resin particles (C) can be obtained by the same method as the resin particles (A). Moreover, it is preferable that a resin particle (C) does not contain a coloring agent and a mold release agent substantially.
In the step (3), as a method of attaching the resin particles (C) containing the polyester resin (c) to the core-shell particles (1), resin particles containing the polyester resin (b) on the core particles in the step (2) ( It is preferable to carry out by a method similar to the method of attaching B).

Aggregation is stopped when the addition of the entire amount of the resin particles (C) has been completed. From the viewpoint of preventing unnecessary aggregation, it is preferable to stop aggregation by adding an aggregation stopper.
As the aggregation terminator, a surfactant is preferable, and an anionic surfactant is more preferable. Anionic surfactants include alkyl ether sulfates, alkyl sulfates, and linear alkyl benzene sulfonates. The aggregation terminators can be used alone or in combination of two or more.
The addition amount of the aggregation stopper is preferably 0.1 to 15 parts by weight with respect to 100 parts by weight of the total resin in the system, from the viewpoint of reducing the aggregation stopping property and the residual of the aggregation stopper in the toner. Preferably it is 0.1-10 weight part, More preferably, it is 0.1-8 weight part. The aggregation terminator may be added in any form, but is preferably added in an aqueous solution from the viewpoint of productivity.
The volume median particle size of the core-shell aggregated particles (2) obtained in the step (3) is preferably 1 to 10 μm, more preferably 2 to 10 μm, still more preferably 3 to 9 μm, from the viewpoint of improving the image quality of the toner. More preferably, it is 4-6 micrometers.

[Joint process]
Since the core-shell particles (2) obtained in the step (3) are mainly physically attached to each other, they are heated to fuse and coalesce the resin particles to obtain coalesced particles. .

The temperature in the system in this step is preferably a temperature equal to or higher than the glass transition temperature of the polyester resin (c) from the viewpoint of promoting fusion and the storage stability of the toner.
Further, from the viewpoint of the chargeability of the toner, the temperature is preferably maintained at a temperature lower than the melting point of the release agent, more preferably maintained at a temperature lower than 5 ° C., and more preferably maintained at a temperature lower than 10 ° C. .
From the above points, the holding temperature in this step is preferably 58 to 69 ° C, more preferably 59 to 67 ° C, and still more preferably 60 to 64 ° C, from the viewpoint of particle fusion.
The holding time in this step is preferably 1 to 24 hours, more preferably 1 to 18 hours, still more preferably 2 to 12 hours, from the viewpoints of particle fusing property, storage stability, chargeability and toner productivity. .

  In this step, it is preferable to confirm the progress of fusion by monitoring the circularity of the coalesced particles to be produced. Circularity is monitored by the method described in the examples. When the circularity reaches 0.955 or more, the cooling is performed and the fusion is stopped. The roundness of the finally obtained coalesced particles is preferably 0.955 to 0.980, more preferably 0.958 to 0.980, and still more preferably, from the viewpoint of chargeability and cleaning properties of the obtained toner. 0.960 to 0.975.

  The volume-median particle size of the coalesced particles obtained in this step is preferably 2 to 10 μm, more preferably 2 to 8 μm, more preferably 2 to 7 μm, and still more preferably 3 to 3, from the viewpoint of improving the image quality of the toner. It is 8 μm, more preferably 4 to 6 μm.

[Post-processing process]
In the present invention, a post-treatment step may be performed after the coalescence step, and it is preferable to obtain toner particles by isolating the coalesced particles.
Since the coalesced particles obtained in the coalescing step are present in the aqueous medium, it is preferable to first perform solid-liquid separation. For solid-liquid separation, a suction filtration method or the like is preferably used.
It is preferable to perform washing after the solid-liquid separation. In order to ensure sufficient charging characteristics and reliability as a toner, it is preferable to perform washing with an acid in order to remove metal ions on the toner surface. Moreover, since it is preferable to remove the added nonionic surfactant, it is preferable to wash with an aqueous solution below the cloud point of the nonionic surfactant. The washing is preferably performed a plurality of times.
Next, it is preferable to perform drying. The drying temperature is preferably set so that the temperature of the coalesced particles itself is 5 ° C. or more lower than the melting point of the release agent. As the drying method, a vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method or the like is preferable. The water content after drying is preferably 1.5% by weight or less, more preferably 1.0% by weight or less, from the viewpoint of reducing the amount of scattered toner and charging properties.

<Toner for electrophotography>
(toner)
The particles obtained by drying and the like can be used as they are as the toner of the present invention, but those surface-treated as described below are preferably used as electrophotographic toners.
The softening point of the obtained toner is preferably 60 to 140 ° C., more preferably 65 to 130 ° C., and still more preferably 70 to 120 ° C., from the viewpoint of low temperature fixability and hot offset resistance of the toner. The glass transition point is preferably 30 to 80 ° C., more preferably 40 to 70 ° C. from the viewpoints of low-temperature fixability, durability, and storage stability.
The circularity of the toner is preferably 0.955 to 0.980, more preferably 0.958 to 0.980, and still more preferably 0.960 to 0, from the viewpoints of storage stability, chargeability and cleaning properties of the toner. .975. The circularity of the toner particles can be measured by the method described later. The circularity of the toner is a value obtained by the ratio of the circumference of the circle equal to the projected area / the circumference of the projected image. The more circular the particles are, the closer the circularity is to 1.
The volume median particle size of the toner is preferably 1 to 10 μm, more preferably 2 to 8 μm, still more preferably 3 to 7 μm, and still more preferably 4 to 6 μm, from the viewpoint of high image quality and productivity of the toner.
The CV value of the toner is preferably 30% or less, more preferably 27% or less, still more preferably 25% or less, and further preferably 22% or less, from the viewpoint of high image quality and productivity.

(External additive)
In the electrophotographic toner of the present invention, the toner particles can be used as the toner as they are, but it is preferable to use a toner obtained by adding a fluidizing agent or the like to the toner particle surface as an external additive. Examples of external additives include hydrophobic silica, titanium oxide fine particles, alumina fine particles, cerium oxide fine particles, inorganic fine particles such as carbon black, acrylic resin such as polycarbonate and polymethyl methacrylate, and polymer fine particles such as silicone resin. Among these, polymer fine particles and hydrophobic silica are preferable, and hydrophobic silica is more preferable.
When the surface treatment of toner particles is performed using an external additive, the amount of the external additive added is preferably 1 to 10 parts by weight, more preferably 100 parts by weight of the toner particles before the treatment with the external additive. 2 to 8 parts by weight, more preferably 3 to 6 parts by weight.
The toner for electrophotography obtained by the present invention can be used as a one-component developer or as a two-component developer by mixing with a carrier.

In relation to the above-described embodiment, the present invention discloses the following electrophotographic toner and a manufacturing method thereof.
[1] An electrophotographic toner comprising a core portion containing a polyester resin (a) and a release agent, an intermediate portion containing a polyester resin (b) and a release agent, and a shell portion containing a polyester resin (c) And 65% by weight or more and less than 90% by weight, preferably 70 to 88% by weight, more preferably 75 to 85% by weight, based on the total amount of the release agent in the toner. Toner.
[2] The content of the release agent in the intermediate part exceeds 10% by weight and is 35% by weight or less, preferably 12-30% by weight, more preferably 15-25%, based on the total amount of the release agent in the toner. The toner for electrophotography according to [1], wherein the toner is% by weight.

[3] The weight ratio ((a) / (b)) of the polyester resin (a) contained in the core part and the polyester resin (b) contained in the intermediate part is 90/10 to 35/65, preferably 75 / The electrophotographic toner according to [1] or [2], wherein the toner is 25 to 35/65, more preferably 75/25 to 45/55, and still more preferably 70/30 to 50/50.
[4] Weight ratio of the polyester resin (a) contained in the core part and the polyester resin (b) contained in the intermediate part to the polyester resin (c) contained in the shell part [(core part + intermediate part) / The shell portion] is 85/15 to 55/45, preferably 80/20 to 60/40, more preferably 75/25 to 60/40, according to any one of the above [1] to [3]. Toner for electrophotography.

[5] The content of the release agent in the core part is 3 to 15% by weight, preferably 4 to 15% by weight, more preferably 5 to 13% by weight, based on the weight of the core part. [4] The electrophotographic toner according to any one of [4].
[6] The content of the release agent in the intermediate part is 1 to 10% by weight, preferably 1 to 8% by weight, more preferably 2 to 7% by weight, based on the weight of the intermediate part. [5] The toner for electrophotography according to any one of [5].
[7] The electrophotographic toner according to any one of [1] to [6], wherein the polyester resin (a) includes a crystalline polyester and an amorphous polyester.

[8] The method for producing an electrophotographic toner according to any one of [1] to [7], comprising the following steps (1) to (3).
Step (1): Step of aggregating resin particles (A) containing polyester resin (a) and release agent particles in an aqueous medium to obtain core particles Step (2): Polyester resin (b Step of obtaining the core-shell particles (1) by adhering the resin particles (B) containing the resin particles (B) and the release agent particles Step (3): Resin particles (C) containing the polyester resin (c) in the core-shell particles (1) Core-shell particles comprising a core part containing a polyester resin (a) and a release agent, an intermediate part containing a polyester resin (b) and a release agent, and a shell part containing a polyester resin (c) Step of obtaining (2)

  Hereinafter, the present invention will be described more specifically with reference to examples and the like. In the following examples and the like, each property value was measured and evaluated by the following method.

[Acid value of polyester]
It measured according to JIS K0070. However, the measurement solvent was a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Softening point and glass transition point of polyester]
(1) Softening point Using a flow tester (manufactured by Shimadzu Corporation, trade name: CFT-500D), a load of 1.96 MPa was applied by a plunger while heating a 1 g sample at a heating rate of 6 ° C / min. And extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of flow tester drop by the flow tester was plotted against the temperature, and the temperature at which half the sample flowed out was taken as the softening point.
(2) Glass transition point A sample was heated to 200 ° C. using a differential scanning calorimeter (manufactured by Parkin Elmer, trade name: Pyris 6 DSC), and cooled to 0 ° C. at a temperature lowering rate of 50 ° C./min. The measurement was performed at a heating rate of 10 ° C./min. When a peak is observed at a temperature 20 ° C. or more lower than the softening point, the peak temperature is measured. When a peak is not observed at a temperature 20 ° C. or higher lower than the softening point, a step is observed. The temperature at the intersection of the tangent line showing the maximum slope of the curve and the extension line of the base line on the high temperature side of the step was taken as the glass transition point.

[Volume Median Particle Size (D ₅₀ ) and Particle Size Distribution of Resin Particles, Release Agent Particles]
(1) Measuring device: Laser diffraction particle size measuring machine (Horiba, Ltd., trade name: LA-920)
(2) Measurement conditions: Distilled water was added to the measurement cell, and the volume-median particle size (D ₅₀ ) was measured at a temperature at which the absorbance falls within an appropriate range. The CV value was calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution / volume median particle size (D ₅₀ )) × 100

[Solid content concentration of resin particle dispersion]
Using an infrared moisture meter (trade name: FD-230, manufactured by Ketto Scientific Laboratory Co., Ltd.), 5 g of the resin particle dispersion was dried at 150 ° C. and measurement mode 96 (monitoring time 2.5 minutes / variation range 0. 05%), the moisture percentage was measured. The solid content concentration was calculated according to the following formula.
Solid content concentration (% by weight) = 100-M
M: moisture (%) = [(W−W ₀ ) / W] × 100
W: Sample weight before measurement (initial sample weight)
W ₀ : Sample weight after measurement (absolute dry weight)

[Volume Median Particle Size (D ₅₀ ) and Fine Powder Amount of Core Particles and Core Shell Particles (1) and (2)]
The volume median particle size of the core particles and the core shell particles (1) and (2) was measured as follows.
Measuring instrument: Coulter Multisizer III (trade name, manufactured by Beckman Coulter)
・ Aperture diameter: 50μm
・ Analysis software: Multisizer III version 3.51 (trade name, manufactured by Beckman Coulter)
Electrolyte: Isoton II (trade name, manufactured by Beckman Coulter)
Measurement conditions: By adding a sample dispersion containing core particles or core-shell particles (1) or (2) to 100 mL of the electrolytic solution, the particle size of 30,000 particles was adjusted to a concentration that can be measured in 20 seconds. Thereafter, 30,000 particles were measured, and the volume median particle size (D ₅₀ ) was determined from the particle size distribution. The ratio of the number of particles of 2 μm or less out of the total number of particles was defined as the fine powder amount (%).

[Volume Median Particle Size (D ₅₀ ) and Particle Size Distribution of Toner (Particles)]
The volume median particle size of the toner (particles) was measured as follows.
The measuring instrument, aperture diameter, analysis software, and electrolyte used were the same as those used for measuring the volume median particle size of the core particles and the core-shell particles (1) and (2).
-Dispersion: Polyoxyethylene lauryl ether (manufactured by Kao Corporation, trade name: Emulgen 109P, HLB: 13.6) was dissolved in the electrolytic solution to obtain a dispersion having a concentration of 5% by weight.
-Dispersion condition: 10 mg of a toner measurement sample is added to 5 mL of the dispersion, and dispersed for 1 minute with an ultrasonic disperser, and then 25 mL of electrolyte is added, and further dispersed for 1 minute with an ultrasonic disperser. A sample dispersion was prepared.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolytic solution to adjust the particle size of 30,000 particles to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured and the particle size distribution thereof. From this, the volume median particle size (D ₅₀ ) was determined.
The CV value (%) was calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution / volume median particle size (D ₅₀ )) × 100

[Circularity of core particles and core-shell particles (1) and (2)]
-Preparation of dispersion liquid: A dispersion liquid diluted with deionized water so that the solid content concentration of the particle dispersion liquid was 0.001 to 0.05% was used as a sample dispersion liquid.
Measurement device: Flow-type particle image analyzer (manufactured by Sysmex Corporation, trade name: FPIA-3000)
・ Measurement mode: HPF measurement mode

[Evaluation of low-temperature fixability of toner]
Using a commercially available printer (trade name: ML5400, manufactured by Oki Data Co., Ltd.) on high-quality paper (Fuji Xerox Co., Ltd., J paper A4 size), the toner adhesion amount on the paper is 0.42 to 0.48 mg. A solid image of / cm ² was output without being fixed at a length of 50 mm, leaving a margin of 5 mm from the top edge of the A4 paper.
Next, the same printer with a variable temperature fixing device was prepared. The temperature of the fixing device was set to 100 ° C., and fixing was performed at a speed of 1.5 seconds per sheet in the A4 longitudinal direction to obtain a printed matter.
In the same manner, the temperature of the fixing device was increased by 5 ° C., and the fixing was performed to obtain a printed matter.
A 500 g weight is applied to the margin at the top of the printed image, after lightly pasting a piece of mending tape (product name: Scotch mending tape 810, width 18 mm) cut to a length of 50 mm. It was loaded and pressed once and again at a speed of 10 mm / sec. Thereafter, the affixed tape was peeled off from the lower end side at a peeling angle of 180 degrees and a speed of 10 mm / second to obtain a printed matter after the tape was peeled off. 30 sheets of high quality paper (Oki Data Co., Ltd., Excellent White Paper A4 size) is placed under the printed material before and after the tape is applied, and the reflected image density of the fixed image portion before and after the tape is applied to each printed material. , Measured using a colorimeter (Gretag-Macbeth, “SpectroEye”, light emission conditions: standard light source D ₅₀ , observation field of view 2 °, density standard DINNB, absolute white standard) Was calculated.
Fixing rate (%) = (Reflected image density after peeling tape / Reflected image density before applying tape) × 100
The temperature at which the fixing rate was 90% or more was defined as the minimum fixing temperature. The lower the minimum fixing temperature, the better the low-temperature fixing property.

[Production of polyester]
Production Example 1
(Production of crystalline polyester (1))
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was purged with nitrogen, and 3936 g of 1,9-nonanediol and 4848 g of sebacic acid were added. While stirring, the temperature was raised to 140 ° C., maintained at 140 ° C. for 3 hours, and then heated from 140 ° C. to 200 ° C. over 10 hours. Thereafter, 50 g of di (2-ethylhexanoic acid) tin was added, and the mixture was further maintained at 200 ° C. for 1 hour. Then, the pressure in the flask was lowered, and maintained at 8.3 kPa for 4 hours to obtain crystalline polyester (1). Obtained. The crystalline polyester (1) obtained had a softening point of 78 ° C., a melting point of 72 ° C., a crystallinity index of 1.1, and an acid value of 19.9 mgKOH / g.

Production Example 2
(Production of amorphous polyester (1))
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 3528 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane (1404 g), terephthalic acid (1248 g), dodecenyl succinic anhydride (1541 g), and dibutyltin oxide (20 g) were added. The temperature was raised to 0 ° C. and maintained at 230 ° C. for 6 hours, and then the pressure in the flask was further lowered and maintained at 8.3 kPa for 1 hour. Then, after cooling to 215 ° C. and returning to atmospheric pressure, 300 g of trimellitic anhydride was added and maintained at 215 ° C. for 1 hour, then the pressure in the flask was further lowered and maintained at 8.3 kPa for 3 hours. Thus, an amorphous polyester (1) was obtained. The glass transition point was 57 ° C., the softening point was 118 ° C., and the crystallinity index was 1.5. The acid value was 19.1 mgKOH / g.

Production Example 3
(Production of amorphous polyester (2))
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 3374 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane (33 g), terephthalic acid (672 g) and dibutyltin oxide (10 g) were added, and the temperature was raised to 230 ° C. with stirring in a nitrogen atmosphere. After maintaining the time, the pressure in the flask was further reduced and maintained at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 696 g of fumaric acid and 0.49 g of tert-butylcatechol were added and maintained at a temperature of 210 ° C. for 5 hours. The amorphous polyester (2) was obtained by maintaining at 3 kPa for 4 hours. The glass transition point was 65 ° C., the softening point was 107 ° C., and the crystallinity index was 1.5. The acid value was 24.4 mgKOH / g.

Production Example 4
(Production of amorphous polyester (3))
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 1750 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, A nitrogen atmosphere containing 1625 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 1145 g of terephthalic acid, 161 g of dodecenyl succinic anhydride, 480 g of trimellitic anhydride, and 10 g of dibutyltin oxide Under stirring, the temperature was raised to 220 ° C. and maintained at 220 ° C. for 5 hours. After confirming that the softening point measured according to ASTM D36-86 reached 120 ° C., the temperature was lowered to stop the reaction. Amorphous polyester (3) was obtained. The glass transition point was 64 ° C., the softening point was 122 ° C., and the crystallinity index was 1.6. The acid value was 21.0 mgKOH / g.

Production Example 5
(Production of amorphous polyester (4))
The inside of the four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 3004 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 996 g of fumaric acid, 2 g of tert-butylcatechol and 8 g of dibutyltin oxide were added, heated to 210 ° C. over 5 hours with stirring in a nitrogen atmosphere, held at 210 ° C. for 2 hours, and then at 8.3 KPa. The reaction was continued until the following softening point was reached to obtain amorphous polyester (4). The glass transition point was 57 ° C., the softening point was 101 ° C., and the crystallinity index was 1.5. The acid value was 22.4 mgKOH / g.

Production Example 6
(Manufacture of master batches containing colorants)
70 parts by weight of fine powder of amorphous polyester (4) obtained in Production Example 5 and a slurry pigment of copper phthalocyanine (manufactured by Dainichi Seika Kogyo Co., Ltd., trade name: ECB-301, solid content 46.2% by weight) Was charged into a Henschel mixer so that the pigment content was 30 parts by weight and mixed for 5 minutes to be wet. Next, this mixture was charged into a kneader mixer and gradually heated. The resin was melted at approximately 90 to 110 ° C. and kneaded in a state where water was mixed, and kneading was continued at 90 to 110 ° C. for 20 minutes while water was evaporated.
Further, the kneading was continued at 120 ° C. to evaporate the remaining water, followed by dehydration drying. Further, kneading was continued at 120 to 130 ° C. for 10 minutes. After cooling, the mixture was further kneaded with a heated three roll, cooled and coarsely crushed to obtain a crushed product (master batch) of a highly concentrated colored composition containing a blue pigment at a concentration of 30% by weight. When this was placed on a slide glass, heated and melted, and observed with a microscope, all pigment particles were finely dispersed, and no coarse particles were observed.

Production Example 7
(Preparation of resin particle dispersion (I-1))
In a flask equipped with a stirrer, 150 g of crystalline polyester (1), 405 g of amorphous polyester (1), 375 g of a masterbatch containing copper phthalocyanine pigment, polyoxyethylene alkyl ether (nonionic surfactant, trade name: Emulgen 150, manufactured by Kao Corp.) 14.1 g, 15 wt% sodium dodecylbenzenesulfonate aqueous solution (anionic surfactant, trade name: Neoperex G-15, manufactured by Kao Corp.) 133 g, 5 wt% water 373 g of an aqueous potassium oxide solution and 17.0 g of ion-exchanged water were added, and the mixture was heated to 95 ° C. and melted with stirring, and mixed at 95 ° C. for 2 hours to obtain a resin mixture.
Next, while stirring, 1995 g of deionized water was added dropwise at a rate of 10 g / min to obtain an emulsion. Next, the obtained emulsion was cooled to 25 ° C., and a resin particle dispersion was obtained through a 200-mesh (mesh 105 μm) wire mesh.
Further, 3348 g of the obtained resin particle dispersion liquid and 36.5 g of an oxazoline group-containing acrylic polymer aqueous solution (manufactured by Nippon Shokubai Co., Ltd., trade name: “Epocross WS-700”; polymer content 25%) are mixed and stirred. The mixture was kept at 95 ° C. for 1 hour. Next, the obtained emulsion was cooled to 25 ° C., passed through a 200-mesh wire mesh, deionized water was added to adjust the solid content to 30% by weight, and the resin particle dispersion (I-1) was dispersed. A liquid was obtained. The volume median particle size of the resin particles (A-1) was 0.167 μm, and the CV value was 31.21%.

Production Example 8
(Preparation of resin particle dispersion (b-1))
In a reaction vessel having an internal volume of 5 liters, 390 g of amorphous polyester (2), 210 g of amorphous polyester (3), polyoxyethylene alkyl ether (nonionic surfactant, trade name: Emulgen 430, Kao 6 g, 15 wt% sodium dodecylbenzenesulfonate aqueous solution (Neopelex G-15) 40 g and 5 wt% potassium hydroxide 278 g were added, and the mixture was heated to 95 ° C and melted with stirring. The mixture was mixed at 0 ° C. for 2 hours to obtain a resin mixture.
Next, 1135 g of deionized water was added dropwise at a rate of 6 g / min while stirring to obtain an emulsion. Next, the obtained emulsion was cooled to 25 ° C., passed through a 200-mesh wire mesh, deionized water was added, the solid content was adjusted to 25% by weight, and the resin particle dispersion (B-1) dispersion was performed. A liquid was obtained. The volume median particle size of the resin particles (B-1) was 0.158 μm, the CV value was 24%, and the glass transition point was 60 ° C.

Production Example 9
(Production of release agent particle dispersion)
2. In a 1 liter beaker, sodium acrylate-sodium maleate copolymer aqueous solution (trade name: Poise 521, effective concentration 40% by weight, manufactured by Kao Corporation) as a sodium polycarboxylate aqueous solution in 200 g of deionized water After 8 g was dissolved, 5 g of carnauba wax (manufactured by Hiroyuki Kato, product name: carnauba wax No. 1, melting point 83 ° C.) and paraffin wax (manufactured by Nippon Seiki Co., Ltd., product name: HNP) −9, melting point 75 ° C.) 45 g was added, and the mixture was melted while maintaining the temperature at 90 to 95 ° C. to obtain a molten mixture in which carnauba wax and paraffin wax were melted together.
The aqueous solution containing the obtained molten mixture was further subjected to a dispersion treatment for 30 minutes with an ultrasonic homogenizer (manufactured by Nippon Seiki Co., Ltd., trade name: US-600T) while maintaining the temperature at 90 to 95 ° C. Then, ion-exchanged water was added thereto to adjust the release agent solid content to 20% by weight to obtain a release agent particle dispersion. The volume median particle size (D ₅₀ ) of the release agent particles in the release agent particle dispersion was 450 nm, and the CV value was 30%.

[Production of toner]
Example 1
(Preparation of Toner A)
Mixing ratio of release agent particle dispersion: core part / intermediate part = 70/30
Blending ratio of resin particle (a-1) dispersion: core part / intermediate part = 50/50
<Step (1): Preparation of core particles>
In a four-necked flask with an internal volume of 2 liters equipped with a dehydrating tube, a stirrer, and a thermocouple, 100 g of 50% by weight of the total amount of the resin particles (ii) dispersion and 50% by weight of deionized water as the dispersed water 31.5 g of water and 12.6 g of a release agent particle dispersion of 70% by weight of the total amount were added and mixed at 25 ° C. Next, while stirring the mixture, an aqueous solution in which 11.5 g of ammonium sulfate was dissolved in 136.8 g of deionized water was added dropwise at 25 ° C. over 10 minutes, and then the temperature was raised to 45 ° C. The temperature was adjusted to 48 ° C. until the particle size became 3.7 μm, and core particles were obtained. The amount of fine powder of the obtained core particles was 2.8%, and the circularity was 0.932.
<Step (2): Preparation of core-shell particles (1)>
In the dispersion of the core particles obtained in the step (1), the remaining 50% by weight of the resin particle (ii) dispersion 100g, the remaining 50% by weight of deionized water 31.5g, and 120g for concentration adjustment. Of deionized water, the remaining 5.4 g of a 30% by weight release agent particle dispersion, and an aqueous solution in which 4.9 g of ammonium sulfate was dissolved in 34.4 g of deionized water were separately added dropwise over 3 hours. As a result, core-shell particles (1) were obtained. The volume-median particle size of the obtained core-shell particles (1) was 4.7 μm, the fine powder amount was 5.1%, and the circularity was 0.940.
<Step (3): Production of core-shell particles (2)>
98.7 g of the resin particle (B-1) dispersion and 31.7 g of deionized water are added dropwise to the dispersion of the core-shell particles (1) obtained in the step (2) over 3 hours, and the temperature is set to 51 ° C. To obtain core-shell particles (2). The volume-median particle size of the obtained core-shell particles (2) was 5.0 μm, the fine powder amount was 4.3%, and the circularity was 0.954.
<Step (4): Preparation of toner particles>
Into a 5 liter four-necked flask equipped with a dehydrating tube, a stirrer and a thermocouple, 589 g of the dispersion of the core-shell particles (2) obtained in step (3), sodium alkyl ether sulfate (anionic surfactant) , Trade name: Emar E27C, manufactured by Kao Corporation) 12.9 g mixed with 2573 g of deionized water was added and mixed. The mixture was heated to 67 ° C. and then held until the circularity reached 0.965 to obtain a raw toner. The obtained raw toner A had a volume-median particle size of 5.0 μm and a fine powder amount of 4.2%. Next, the dispersion was cooled to 25 ° C., and the solid content was separated by suction filtration while being kept at 25 ° C., washed with deionized water, and dried at 33 ° C. to obtain toner particles. 100 parts by weight of the toner particles, 2.5 parts by weight of hydrophobic silica (trade name: RY50, manufactured by Nippon Aerosil Co., Ltd., average particle size: 0.04 μm), and hydrophobic silica (trade name: Cabo Seal TS720, Cabot Corporation) Manufactured, average particle size; 0.012 μm) was put in a Henschel mixer, stirred, and passed through a 150-mesh sieve to obtain toner A. Table 1 shows the results of low-temperature fixability of the obtained toner and the circularity and fine powder amount at the time of preparation of the core-shell particles (1).

Example 2
(Preparation of Toner B)
Other than changing the blending ratio of the release agent particle dispersion to core / intermediate part = 80/20, and changing the blending ratio of the resin particle (ii-1) dispersion to core / intermediate part = 60/40 Obtained toner B in the same manner as in Example 1. Table 1 shows the results of low-temperature fixability of the obtained toner and the circularity and fine powder amount at the time of preparation of the core-shell particles (1).

Example 3
(Preparation of toner C)
Other than changing the blending ratio of the release agent particle dispersion to core / intermediate part = 80/20 and changing the blending ratio of the resin particle (ii-1) dispersion to core / intermediate part = 40/60 In the same manner as in Example 1, a toner C was obtained. Table 1 shows the results of low-temperature fixability of the obtained toner and the circularity and fine powder amount at the time of preparation of the core-shell particles (1).

Example 4
(Preparation of Toner D)
Other than changing the blending ratio of the release agent particle dispersion to core / intermediate part = 80/20 and changing the blending ratio of the resin particle (i-1) dispersion to core / intermediate part = 80/20 Obtained toner D in the same manner as in Example 1. Table 1 shows the results of low-temperature fixability of the obtained toner and the circularity and fine powder amount at the time of preparation of the core-shell particles (1).

Example 5
(Production of Toner E)
Other than changing the blending ratio of the release agent particle dispersion to core / intermediate part = 87/13 and changing the blending ratio of the resin particle (ii-1) dispersion to core / intermediate part = 87/13 Obtained Toner E in the same manner as in Example 1. Table 1 shows the results of low-temperature fixability of the obtained toner and the circularity and fine powder amount at the time of preparation of the core-shell particles (1).

Comparative Example 1
(Production of Toner F)
Toner F was obtained in the same manner as in Example 1 except that the mixing ratio of the release agent particle dispersion was changed to core / intermediate part = 100/0. Table 1 shows the results of low-temperature fixability of the obtained toner and the circularity and fine powder amount at the time of preparation of the core-shell particles (1).

Comparative Example 2
(Preparation of toner G)
Other than changing the blending ratio of the release agent particle dispersion to core / intermediate part = 100/0, and changing the blending ratio of the resin particle (i-1) dispersion to core / intermediate part = 60/40. In the same manner as in Example 1, a toner G was obtained. Table 1 shows the results of low-temperature fixability of the obtained toner and the circularity and fine powder amount at the time of preparation of the core-shell particles (1).

Comparative Example 3
(Preparation of Toner H)
Toner H was obtained in the same manner as in Example 1 except that the blending ratio of the release agent particle dispersion was changed to core / intermediate part = 60/40. Table 1 shows the results of low-temperature fixability of the obtained toner and the circularity and fine powder amount at the time of preparation of the core-shell particles (1).

Comparative Example 4
(Preparation of Toner I)
Toner I was obtained in the same manner as in Example 1 except that the blending ratio of the release agent particle dispersion was changed to core / intermediate part = 50/50. Table 1 shows the results of low-temperature fixability of the obtained toner and the circularity and fine powder amount at the time of preparation of the core-shell particles (1).

Comparative Example 5
(Production of Toner J)
Other than changing the blending ratio of the release agent particle dispersion to core part / intermediate part = 30/70 and changing the blending ratio of the resin particle (ii-1) dispersion to core part / intermediate part = 30/70 Tried to produce toner J in the same manner as in Example 1. However, excessive aggregation occurred during the preparation of the core particles, and toner J was not obtained.

  From Table 1, the toners of Comparative Examples 1 to 5 have insufficient low-temperature fixability and / or suppression of the amount of fine powder, whereas the electrophotographic toners of the examples all have a small amount of fine powder and low temperature. It can be seen that the fixing property is excellent. In particular, comparison between Example 1 and Comparative Examples 3 and 4 shows that when the content ratio of the core part of the release agent is less than 65% by weight, the amount of fine powder is not sufficiently suppressed.

  Since the electrophotographic toner obtained by the production method of the present invention has good low-temperature fixability and particle uniformity, it is used as an electrophotographic toner used in electrophotography, electrostatic recording, electrostatic printing, and the like. It can be used suitably. According to the method of the present invention, a toner having such characteristics can be produced efficiently.

Claims (6)

Same as polyester resin (a) and core part containing release agent, polyester resin (b) which is the same or different from polyester resin (a) and intermediate part containing release agent, and polyester resin (a) Or an electrophotographic toner comprising a shell portion containing a polyester resin (c) which is a different resin ,
The content of the release agent contained in the core part, the intermediate part, and the shell part is 3 to 15% by weight with respect to the core part weight, and 1 to 10% by weight with respect to the intermediate part weight, respectively. An electrophotographic toner that is 0.5% by weight or less with respect to the weight, and 65% by weight or more and less than 90% by weight with respect to the total amount of the release agent in the toner.   2. The electrophotographic toner according to claim 1, wherein the content of the release agent in the intermediate part is more than 10% by weight and not more than 35% by weight with respect to the total amount of the release agent in the toner.   The weight ratio ((a) / (b)) of the polyester resin (a) contained in the core part and the polyester resin (b) contained in the intermediate part is 90/10 to 35/65. The toner for electrophotography described in 1.   Weight ratio of the polyester resin (a) contained in the core part and the polyester resin (b) contained in the intermediate part to the polyester resin (c) contained in the shell part [(core part + intermediate part) / shell part] The toner for electrophotography according to claim 1, wherein is 85/15 to 55/45. Polyester resin (a) comprises a crystalline polyester and an amorphous polyester, toner for electrophotography according to any one of claims 1-4. Following steps (1) including to (3), the production method of toner for electrophotography according to any one of claims 1-5.
Step (1): Step of aggregating resin particles (A) containing polyester resin (a) and release agent particles in an aqueous medium to obtain core particles Step (2): Polyester resin (b Step of obtaining the core-shell particles (1) by adhering the resin particles (B) containing the resin particles (B) and the release agent particles Step (3): Resin particles (C) containing the polyester resin (c) in the core-shell particles (1) Core-shell particles comprising a core part containing a polyester resin (a) and a release agent, an intermediate part containing a polyester resin (b) and a release agent, and a shell part containing a polyester resin (c) Step of obtaining (2)